/Engine/Source/Runtime/Engine/Classes/Materials/Material.h
Get the expression input for the given property
FExpressionInput* A pointer to the expression input of the property specified, or NULL if an invalid property was requested (some properties have been removed from UI, those return NULL).
[FExpressionInput](API\Runtime\Engine\FExpressionInput) * GetExpressionInputForProperty ( EMaterialProperty InProperty )